Speakerphones are used in many settings by both individuals and businesses to facilitate communication between multiple parties and to provide a hands-free setting. Speakerphones are frequently used in automobiles so that a user will not have to handle a receiver while operating the automobile. Many speakerphones are half duplex speakerphones, in which only one party can occupy a communication channel at a time. Once one party gets the channel, the other party must wait until the channel is free to proceed.
If a speakerphone is used in an environment in which the noise level increases suddenly, outbound audio may become temporarily muted. For example, automobile acceleration increases the overall noise level such as in a car, such that when an automobile starts moving, the outbound audio will become muted for a period of time that may encompass 8 to 10 seconds.
The muting is caused by an inbound voice activated detector (VAD) detecting the sudden increase in noise as near-end speech. Since the VAD detects speech rather than noise, it locks the inbound channel. It takes about 8 to 10 seconds for the VAD to revert back to its normal operation. The VAD is unable to adapt quickly enough to recognize the increase in the background noise level. This causes the noise level to break in and lock the channel. Accordingly, a technique is needed for more quickly detecting the increased noise level and releasing the channel for possible outbound use to avoid blocking outbound speech.